Thank you!Yes it will be overwritten with the stock recovery, so you would need to flash TWRP again.
If you are using magisk you can also use this https://forum.xda-developers.com/t/...ices-platforms.2239421/page-102#post-77770683 module by @osm0sis
Yes, I plan on installing Magisk. I know, this is not directly the topic of this thread but still related to my question:
Lets say I installed TWRP and Magisk and there is an OTA available and I want to stay rooted: Do I need to flash the original boot.img before flashing the OTA or not? (And after the OTA I would reinstall Magisk in the manager app)
Some guides do say to flash the original boot.img, some not. I don't understand in which cases this needs to be done?